1. Technical Field
This invention is directed generally to bar screens for cleaning debris from a bar rack extended across a liquid stream such as the waste water stream entering a water treatment facility or the intake water stream for an electrical power plant. More particularly, the present invention is directed to a roving bar screen which is laterally movable across the top of a bar rack for positively cleaning and removing debris from the bar rack at different lateral positions therealong and with minimum vertical clearance requirements.
2. Description of the Prior Art
In the past, the screens for cleaning large bar racks generally required stationary equipment extending below the surface of the water under at least peak flow conditions, which equipment employed chains, cables and/or multiple rakes which were expensive and difficult to install and maintain. When the rake head of such equipment would engage too heavy of a load, the chain or cable drive system would either give out or cause the rake head to jump over the obstruction without removing it. It has been known to mount a rake on the end of a straight cylinder but that type of equipment has been limited to relatively small bar racks having a height of only approximately six feet as opposed to the 40-foot tall bar racks known for use in waste water treatment plants today.
Accordingly, a primary object of the invention is to provide an improved bar screen wherein the rake head is supported on the end of a telescoping arm mounted on a traveling framework capable of movement across the top of the bar rack for cleaning the bar rack in stages.
Another object of the invention is to provide such a roving bar screen wherein the vertical clearance requirements of the traveling framework are substantially less than the maximum extension of the telescoping arm on which the rake head is mounted.
Another object is to provide such a roving bar screen wherein the telescoping arm is designed to resist both bending and twisting forces.
A related object is to provide such a roving bar screen which is particularly adapted for indoor installation where long extension of the arm is required but ceiling height is limited.
Another object is to provide such a roving bar screen wherein the telescoping arm is actuated by a multi-stage hydraulic cylinder for positive extension and retraction even upon encountering heavy loads.
Another object of the invention is to provide such a roving bar screen with no moving parts located permanently below the surface of the water under peak flow conditions.
Another object of the invention is to provide such a roving bar screen designed to insure that maintenance can be provided at the operating floor level of the traveling framework.
Another object is to provide such a roving bar screen which is capable of both manual and automatic operation.
Another object is to provide such a roving bar screen wherein the framework and functional assemblies, both fixed and moving, are designed to provide maximum efficiency and long life.